I am looking to replace the old foam insulation in between the heat pump and air handler. Foam (polyethylene) insulation is around $2 per 4' and rubber (elastomeric) insulation is around $7 per 4' at Home Depot. Both are self sealing. Is there any advantage to spending the extra money on the rubber insulation? Life expectancy, insulating properties?
PE insulation lasts more than 25 years with the same insulating (lambda) value. PE is non-toxic, does not emit toxic black smoke, never absorbs water, etc etc.
Rubber (elastomeric) may be easier to install, but disintegrates due to the Chlorine in the material (in contact with water it creates hydrochloric acid which corrodes steel - there is now a very expensive non-halogen rubber to solve that problem).
If you choose PE, you are set for life. You choose rubber, and your insulating value will drop by 25% over the period of 5 years, and you need to replace the stuff within 6 years.